How to shrinkwrap without losing sculpted details
I downloaded your file and found a way to achieve the result you want.
You need to create a lattice object and give it enough subdivisions for it to be conformed to the surface of your sphere. Then put only the bottom half of one of your leaf inside the lattice.


Then you can use the lattice modifier on your leaf to reference the lattice object you just created. Finally, apply the shrinkwrap modifier to the lattice object and it works. Now, you just have to repeat the process for the second leaf. I should also inform you that I had to scale up your objects to make it work since they were very small.
This forum post helped me : https://blenderartists.org/t/project-object-onto-another-and-keep-the-thickness/600541/5
Here's the modified scene :

The Result :